For digital further processing or distribution of films which have been recorded by conventional film cameras, the developed films are digitized. In this case, the film is for example moved continuously past a sensor which scans the film line by line. In this case, a scanned line comprises a multiplicity of successive pixels or pixels lying next to one another. Successively scanned lines in each case produce an image. It is also possible to scan the images of a film by means of an area-array sensor. In this case, the pixels of all the lines and columns which digitally represent the image are scanned simultaneously by a sensor.
It is usually possible for different film formats to be scanned in film scanners. Customary film formats are e.g. 16 mm, 35 mm and 70 mm films. Modern film scanners can nowadays scan the images of the films with 4000 or more pixels per line. Consequently, a scanned image of a conventional film in an aspect ratio of 16:9 results, for example, in digitized images which comprise 4000 pixels in one line and 2250 lines per image. The scanning quality is usually controlled by an operator during scanning. Owing to the high resolution required for the control monitor, computer screens are usually used. Computer screens are optimized for image reproduction with a specific number of lines and pixels per line. The resulting resolutions of the screen are, for example, 800×600, 1280×1024 or 1600×1200 pixels for monitors in a 4:3 aspect ratio. Analog tube monitors, in the case where an analog video signal is fed in, can theoretically also represent resolutions between these values, but the maximum resolution is limited in this case, too, e.g. by the slotted mask or shadowmask used. The resolution of LCD screens, the use of which has become more and more prevalent recently, is defined on fundamental grounds. Consequently, with both types of monitors, it is not possible to satisfactorily represent images with a considerably higher resolution than the resolution of the monitor. If an image having a higher resolution is intended to be represented on a screen having a lower resolution, pixels must be obviated in the horizontal and vertical image directions. However, omitting pixels means that the size of the image to be represented is reduced, under certain circumstances, such that said image does not cover the entire available screen region in terms of width and/or height. Thus, by way of example, an image having a resolution of 1000 pixels per line and 560 lines per image would be enabled to be represented on a screen having a resolution of 800×600 pixels by every second pixel being obviated in the horizontal and vertical directions. Although the resulting image having 500×280 pixels would now be able to be represented on the screen, it would not utilize the usable size of the screen. Although it would be possible to scale only the horizontal resolution, i.e. to omit pixels only in the lines, the image would thereby be distorted undesirably. Moreover, omitting individual pixels means that individual fine details of the image cannot be represented on the monitor and thus cannot be controlled by the user either. This relates in particular to thin lines lying parallel to the scanning raster of the film scanner. Therefore it is desirable to employ a method which enables digitized images having a higher resolution to be displayed without distortion with the largest possible representation size on a screen having a lower resolution and nevertheless as many image details as possible to be made visible. Furthermore, it is desirable to use a circuit which carries out the scaling in real time.